The goal of this proposal is to build upon the technical knowledge gaine from the first submission concerning MRA acquisition parameters and techniques and apply this to a large patient base at the Cleveland Clini to address specific clinical questions concerning cerebrovascular disease. Initial efforts will utilize newly acquired technical capability to realize the theoretical improvements predicted by the firs proposal. This will include an assessment of the relative effectiveness and compatibility of MRA techniques to improve vessel contrast and the impact of enhanced gradient performance on flow artifacts, spatial resolution or reduced examination time. The clinical portion of the proposal is directed towards the implementation of these refinements in well designed prospective clinical studies. We will test the hypothesis that optimized time-of-flight MRA is of sufficient accuracy to replace intra-arterial angiography prior to carotid endarterectomy. We will als test the effectiveness and evaluate the benefit of MRA as a screening tool for the detection of unruptured intracranial aneurysms in high risk patient populations. This clinical data will provide a rational basis to assess MRA's role in the routine diagnosis and management of cerebrovascular disease. In addition, these studies should permit the preliminary evaluation of MRA's economic impact and role in patient outcome by providing more accurate natural history data and consequent improved clinical decision making.